Early childhood caries (ECC) is a significant national problem that disproportionately affects low- income children, and its prevalence is increasing. Because it is difficult to reach pre-school aged children for caries prevention, thirty-three state Medicaid programs have implemented reimbursement to medical primary care providers (PCPs) to provide early childhood caries preventive services (ECCPS). However, states report slow rates of uptake. Further, little is known about the child, provider, and community factors associated with the receipt of ECCPS and the effect on subsequent dental service use. The purpose of this study is to evaluate the effect of PCP reimbursement on access to preventive oral health services in early childhood for Medicaid-enrolled children. Our central hypothesis is that these policies have improved access to ECCPS with variations in policy effectiveness based on child and community characteristics. To test our hypothesis, we will use secondary data provided by the Florida and Texas Medicaid programs to accomplish the following specific aims: (1) to compare receipt of ECCPS before and after PCP reimbursement and examine whether there are variations among particularly vulnerable subgroups of children, including children with special health care needs and racial/ethnic minorities; (2) to examine the impact of PCP reimbursement on access to ECCPS in high-risk communities, and (3) to evaluate whether receipt of ECCPS from a medical PCP is associated with an increased likelihood of seeing a dental provider. Secondary data sources include child-level longitudinal enrollment databases linked to claims and encounter data for children 0-3 years old enrolled in Florida and Texas Medicaid. Multivariable regression analyses and geographic information systems techniques will be used to evaluate policy impacts and variations by child and community characteristics. The proposed research will provide important information about how effective current policies are in achieving their objectives and whether there are variations in policy effectiveness among Medicaid subpopulations. This information is a critical first step in developing actionable strategies to improve the performance of ECC prevention programs and reversing the trend of increasing ECC prevalence. PUBLIC HEALTH RELEVANCE: The proposed study promotes NIDCR Strategic Goal 4: Apply Rigorous, Multidisciplinary Research Approaches to Eliminate Disparities in Oral, Dental and Craniofacial Health and the Healthy People 2020 (proposed) goals to increase the proportion of low-income children and adolescents who receive preventive dental services (OH HP2020-4) and to reduce the proportion of children and adolescents who have dental caries in their primary or permanent teeth (OH HP2020-6). Specifically, this study examines the effect of medical provider reimbursement on access to early childhood caries preventive services and subsequent dental use among Medicaid enrollees. The findings from this study will inform the development of targeted interventions to improve the effectiveness of early childhood caries prevention programs and reverse the trend of increasing caries prevalence among pre-school aged children.